some exhaust issues

By shift_450R, Posted April 15, 2009

i just picked up and 04 yz250 and the only problems it had were that the exhaust was leaking. it has a full pro cicuit exhaust. it leaks from the head to the main pipe. he said theres a donut or a gasket that goes there that is missing from it. what would i need to get? and is there a clamp or anything i need for where the pipe meets the silencer? its loose. thanks

By RBYM, Posted April 15, 2009

They have round o-rings to make a seal in the cylinder. Check out the thumpertalk store, they should have them.

By bergermeister, Posted April 15, 2009

What you will need is Yamaha part number: 5MW-14642-00-00. You will need two of these. They're only $5.29 each in the thumperstore.

By breedlove23, Posted April 15, 2009

Someone had written a pretty good attachment procedure that cleared my leak up...Use some hi temp sealant at the gaps pipe to head, and silenencer to pipe. Put your pipe on with the new o-rings and springs and do not tighten the bolt down that holds the pipe to the bike. Also loosely attach your silencer to the bike...you can add the collar that attaches the two. Fire up your ride and let the exhaust "settle" this will ensure a proper fit and no leaks. Make sure to tighten all of your bolts up when done.

Sign in

Similar Content

Hi all, First post here. I need some help.
Ive just bought an 05 yz 125 for a good price but it needs some work. One of the forks has some pretty severe pitting of the chrome on the stanchion towards the bottom near the brake caliper mount.
Ive found a pair of good condition forks from an 04 yz250 for a very good price, from the research ive done its seems that both the 04 & 05 forks are 48mm but are different, with the 05 fork regarded as being better than the 04, but not as good as the 06 + sss forks.
Im looking for the cheapest way to get me riding, Will I be able to make the 04 forks work with my 05 triple clamps, brakes, wheel, axle, spacers etc? If not does anyone know what hardware id need to make it work?
Finally, as a last resort, does anyone know if i could swap the stanchion from the 04 fork into my 05 forks?
Thanks, Andrew

I bought a 2006 YZ250, have ridden it 5 times. It needs some tuning, but I am not sure I'm keeping it so don't want to spend much on it.
Has fmf gnarly expansion chamber and turbine core silencer.
I ride about 1000 feet above sea level.
I'm going to clean the carb and check the jetting. What is a good jetting for me? 85 main jet?
Also check the reeds. Is there a big difference between getting aftermarket reed cage and reeds or just getting a cheap aftermarket set of reeds that fit the stock cage ie. Boyesen Power Reeds?
The other things I'm going to do is permatex all the joints in the exhaust system and a compression test. It was 220psi 5 rides ago so I'm guessing itll be fine. Its bogging a bit but I'm thinking its carb and definitely exhaust joint related.
Let me know if I'm overlooking anything that could make the bike run crisper and more bottom end without throwing much money on parts

I bought a 2006 YZ250, have ridden it 5 times. It needs some tuning, but I am not sure I'm keeping it so don't want to spend much on it.
Has fmf gnarly expansion chamber and turbine core silencer.
I ride about 1000 feet above sea level.
I'm going to clean the carb and check the jetting. What is a good jetting for me? 85 main jet?
Also check the reeds. Is there a big difference between getting aftermarket reed cage and reeds or just getting a cheap aftermarket set of reeds that fit the stock cage ie. Boyesen Power Reeds?
The other things I'm going to do is permatex all the joints in the exhaust system and a compression test. It was 220psi 5 rides ago so I'm guessing itll be fine. Its bogging a bit but I'm thinking its carb and definitely exhaust joint related.
Let me know if I'm overlooking anything that could make the bike run crisper and more bottom end without throwing much money on parts

Hey guys, I have a 2003 cr125 I bought a couple weeks ago and I'm having a problem with it. The spark plugs die every about 15 minutes, with hotter plugs it will last about 45 minutes. I herd that if the timing is off it can over heat the plugs and burn out the the resistor. Is there any truth to that? The reason I thinks it's not fouling is because when the plug dies it gives no spark no matter how much you clean it, And it shorts out.

A tiny clear rubber tube on bottom of carb. On bottom sort of on side, by floats, the other end just hanging down. Was it always like this? Or does the other end go somewhere? Today after multiple trys with kick, choke on/off ,,,fuel keeps pouring out the tube. This bike has always been hard to start. Thanx guys!